Brake rotor



April 14, 1931. R. J. NORTON 1,800,900

BRAKE ROTOR Filed Nov. 23, 1928 F-IGZI.

I ll. Mtlfttlllhl, (OW WAEHINWEON, DISTRICT 018 GOL'UJLWS BRAKE no'ron Application flied November as, that.

l his invention relates to brake rotors and more particularly to brake drums on automotive vehicles.

Certain characteristics are requisite for automotive brakedrums. These brake members should be of suficient strength and ri idity to withstand the abrasive torces of rictional brahng and the distortive efiects of the expansion or contraction oi juxtaposed elem meets. its used on automobiles with an internal expandin brake mechanism, the brake drum structure includes, as an almost essential adjunct, a bachn plate or dust plate which serves to close o the open face of the drum to protect the interior brake mechanism :lrom dirt, mud and water. Since this structure comprises two metallic members, one of which is subjected to relatively wide ranges oi temperatures, it has been found necessary to allow relatively large initial clearances between those portions of the drum and backing plate which term the closure. As a result, during early runs and before the brake drum has been heated up, the gap presented hetween the two members may permit the access oi? water, dust, etc.

is an object of the resent invention to so construct the brake n; rum that the initial clearance hereinbeiore reierred to, may be my out down to a practical minimum and at the same time to impart to the brake drum other :rlesirable properties.

The invention is herein shown and deribed with particular reference to a drum ing a radially extending marginal lip at o .n lace, although it will be understood principles of the invention are aptble to other specific 1 of drums.

adly considered, the invention com rethe idea ct" tormin that ortion o the cm which is juxtapose to the coking plate a naterial having a lower coeficient of exr n (and preferably of a higher tensile th) than c remainder of the ierrugiiua drum. The preferred embodiment of in vention 0 comprises first pressin or roping out a i s 2 cm a suitable blan of lraw steel and then treating the portion to in such a manner as will im o art teriail N0. 353L453.

expansibility. @no method of doing this is to form a marginal lip of a term-nickel having approximately 36.5% of nickel. To enable a ready comprehension of the invention, 1 have shown preferred embodiments of it in the accompanying drawings. in these the same reference numerals refer to similar parts throughout the several view of which:

it ig. 1 is an elevation of the drum.

Fig. 2 is a section taken on line 2-2 of Fig. 1.

Fig. 3 is a sectional view of a modified form of the invention.

As indicated hereinbefore, the invention is applicable to any type of drum which is typified in the drawing, as of the conventional type used in automotive construction. This comprises a head or securing flange '1, rovided with the apertures 2 through w' ich may pass the securing means which attach the drum to the wheels. Integral with the head is a cylindrical braking flange 3. This drum may be made up by stamping out from a suitable blank of metal.

Une method of carrying out this, comprises casting an annulus of metal, having the desired properties, upon the edge ofthe braking flange so as to form an integral 'oint. To do this, the edge of the braking ange may be tapered and upturned, as indicated at l, to term a chaplet or core 4. The drum may be placed within a suitable mold and the molten invar cast about the protrusion 4 so as to form the lip or flange 5. This is shown as comprising a radially extending flan e, but it will be understood that it may be o any desired configuration.

Durin the casting operation the molten metal wi l tend to fuse the adjacent section of the drum in and around the portion 4:, and will therefore provide a tused zone which on solidification will present an inte ral structure. In addition to this integra ity of structure, with its concomitant advantages, it will be observed that this method advan tageously utilizes the shrinkage factor of the cast part to place the edge of the drum under a degree of compression. This not only enhances the rigidity imparted by an anarly extending flange but also acts to Mil preserve the concentricity bf the drum byapplying a substantiall constant, uniform radial force thereto. y this method, a line of cleavage between the two metallic sections is eliminated and in place of this there is substituted a relatively wide zone of fusion.

If desired, the marginal lip may be applied directly to the braking flange without making use of a casting method. An examle of such a procedure is shown in Fig. 3. this case the drum is stamped out to form the head 1 and a. cylindrical flange 3. The braking flange may terminate in a squared edge to which the annulus of the difler'ential metal 6 may be attached. This annulus may comprise a ferro-nickel of the invar range, or any othermetal having the desired characteristics, and may separately be made up and then attached to the drum. In the preferred method, the annulus is connected or attached to the drum b a fusion joint indicated at 7.

This may be one by seam or spot welding,

brazing, soldering and the like. After such a treatment, the mar 'nal flange 6 is, in part 5 at least, integrally joined to the brake drum, and if desired, a full circumferential fusion joint may be obtainedthus, as pointed out, eliminatlng any line o cleavage between the two metals.

After such a treatment, the brake drum in effect com rises two integral metallic sections of di erential characteristics. The major portion of the brake drum being of a pressed steel having I the characteristics of metals of a similar composition and the marginal lip comprising a metallic com osition,"

or alloy havinga lower coefficient 0 expan-' sion and greater tensile strength. As a re; sult of this, the marginal lip serves as a rigid-.

ifying element at the open face of the drum and. also cuts down the degree of expansion which obtains in ordinary structures. Hence, when the drum and backing plate are first associated, only a very slight clearance need ve small gap existing between the drum an the backing"plate, an effective closure is thereby presented which will exclude substantially all extraneous foreign matter.

There has been described methods which comprise forming on the drum a marginal lip of the ferro nickel type. This material is chosen as one which is characterized by the desired properties but'is given, and is to be taken, as merely'indicative of a wide number of materials which may be employed. Thus, if it is desired to merely rigidlfy the brake drum, the flange may be so treated as to increase its tensile strength. Or again, if desired, the marginal lip which. is to be attached, may be so treated or chosen so as to impart merely low thermal expansibility.-.

The invention is considered as residing broadly in the concept or providi'n an inw tegral (and by that is meant initial integral be allowed between them. Because of the or subsequently made integral) open edge on the brake drum which is of a higher'tensile strength and a lower coeflicient of thermal expansion than the main portion of the brake drum. g

It will be understood that the methods out lined are susceptible of a wide range of permissive variations. Thus, it has been pointed out that bycasting on the flange, advantageous useis made of the shrinkage factor of the cast metal. The value of this factor may be varied by heating the braking flange to adjust the temperature differential between the two metals. Thus, if a large shrinkage factor is desired, the braking flange of the drum may be maintained at a relatively low temperature, whereas ifonly a slight'compressive force is soug t, the temperature of the drum may be considerably raised so as to expand -it, and thus, in part, neutralize or compensate for the shrinkage of the cast portion. The particular thermal conditions of the operation will, of course, depend on the physical characteristics of the. metals involved.

It is to be noted in passing that no disadvantageous effects need result froin the expansivity differential. While it is true that the braking flange will tend to expand more than the marginal lip and will, therefore, be stressed, this stress is distributed over a relatively wide area, and hence suflicient tolerance is provided.

It will also be appreciated that by accurately controlling the thermal conditions of the casting operation, the molten metal may v,be made to solidify under substantially uniform conditions throughout the. circumference of the drum. In cases where alloys are used which present selective solidification phenomena, the resulting hetero neity may be relieved by a suitable annea ing stepso that the pressure exerted u on the edge of the drum may be substantia ly uniform. In this manner, the exterior rin may be made to act on the drum with a su tantially uniform radial thrust throughout its circumference and thus effectively maintain concentricity of the dnu-m as well as checking the tendency towafd abell mouthed ex ansion. By thus maintainin the braking ange in substantially truly circular form, the maximum extent of efiective drum'braking surface is presented.

Governed by these considerations, those skilled in the art may, by utilizing the methods suggested or even by varying very widely from these, providea brake drum which pre;

sents these new and improved characteristics and while specific structures and methods have been suggested, it is to be understood that these are to be taken as merely indicative of how the indicated improved results may be obtained; hence, the invention is considered to comprehend anycomparable procill? t it nsoaeo esses or means which may be employed to se cure these improved results.

it claim:

l. A pressed steel brake drum having a. marginal. lip of a material of diflerent thermal characteristics than the body of the drum.

2. A brake drum comprising a pressed steel head and flange and a marginal lip on the flange comprising a material of lower 00- eficient of thermal expansion than the head portion.

3. it. hrake drum comprising a supporting part and a braking flange, a marginal edge on the braking flange of a material of lower coetflcient of expansion and higher tensile strength than the material of the flange.

l. brake drum comprising a supporting part and a cylindrical braking flange of lerrnginous material, a marginal edge on the comprising a lerro-nickel alloy.

5. it hralre drum comprising a cylindrical hralring flange and a marginal therelfor o'l'r a material of a higher tens: is strength than and fused to the flange.

brake drum comprising a cylindrical lirairing flange and a marginal edge therefor, oil diflerent material having lower coeflicient oi enpansion.

it. A. hralre comprising a loralring flange marginal edge tlierelfor, comprising a erial or a different coe'llicient 0t exparn sion rinsed to the braking flange.

A brake drum comprising a braking flange, a ring'lilre portion of a different mater'al fused to the flange, said material having higher tensile strength than the material the flange.

t). A. brake drum comprising a braking flange, a ring-like portion cl? a different material tnsed to the flange, said material having a lower coeflicient of expansion than the material of the flange.

10. A brake drum comprising a braking flange, a ring-like portion of a different material fused to the flange, said material havin. a lower coeflicient of expansion and hi. her tensile strength than the material the flange. .l'l. it loralre drum comprising a ferruginons braking flange and a rigiditying flange of a nickeliferous metal cast thereon. 12A brake drum comprising a steel braking flange and an integral form-nickel portion.

l3. it loralte drum comprising a steel braking flange having an invar marginal l t. A lorake drum comprising a braking flange oi. a pressed metal and an integral portion oil" cast metal.

l5. .fl. hralre drum comprising a braking fl an' e of pressed metal having an integral nmn ,ial section of a. metallic metre rial of dierent physical characteristics fused to and adapted to rigidity the drum.

16. A brake part com rising a ferruginons member and a nonerruginous mem her fused thereto.

17. A loralre part comprising a ferrugmous member and a nickeliferous metal cast thereon.

18. A brake part comprising a composite terruginous and nickeli'lerous' member.

in testimon whereof I afix my signature.

hLAYll/lOND J. NORTON. 

